(a) Field of the Invention
This invention relates to a novel process for the preparation of [bis(substituted aryl)(indolyl)]methanes and [(substituted aryl)(heteryl)(indolyl)methanes useful in the art of carbonless duplicating as, for example, in pressure-sensitive systems and in thermal marking systems; and to novel [(aryl)(disubstituted aminoaryl)(indolyl)]methanes, [(aryl)(disubstituted aminoaryl)(indolyl carboxylic acid)]methanes and [(aryl)(julolidino)(indolyl)]methanes produced by said process.
(b) Description of the Prior Art
Several classes of organic compounds of widely diverse structural types are known to be useful as colorless precursors for carbonless duplicating systems. Among the more important classes, there may be named phenothiazines, for example, benzoyl leuco methylene blue; phthalides, for example, crystal violet lactone; fluorans, for example, 2'-anilino-6'-diethylaminofluoran and 2'-dibenzylamino-6'-diethylaminofluoran; arylsulfinate salts of Michler's Hydrol; and various other types of colorless precursors currently employed in commercially-accepted carbonless copy systems. Typical of the many such systems taught in the prior art are those described in U.S. Pat. Nos. 2,712,507, 2,800,457, 3,041,289 and 4,000,087, which issued July 5, 1955, July 23, 1957, June 26, 1962 and Dec. 28, 1976, respectively. Many of the color formers in the prior art suffer one or more disadvantages such as low tinctorial strength, poor light stability, low resistance to sublimation, low susceptibility to copiability of the color-developed form in standard office copying machines, for example, a xerographic type of copier, and low solubility in common organic solvents, the latter disadvantage thus requiring the use of specialized and expensive solvents in order to obtain microencapsulated solutions of sufficient concentration for use in pressure-sensitive copying systems.
In the prior art, benzoyl leuco methylene blue, related derivatives of phenothiazines, and analogous compounds derived from phenothiazines have been used as slow developing color formers for use in carbonless duplicating systems in combination with additional art recognized instant color-forming compounds.
One of the oldest combinations of color-forming compounds used in pressure-sensitive systems is a mixture of crystal violet lactone and benzoyl leuco methylene blue. The crystal violet lactone is responsible for providing the initial image which is, however, very unstable to light and moisture. These deficiencies are overcome by the use of benzoyl leuco methylene blue which develops slowly upon exposure to air, providing a green-blue image to augment or replace that of the fading crystal violet lactone. The developed image of the benzoyl leuco methylene blue is extremely light stable, but is rather green in shade, is lacking in contrast quality, and therefore is unsatisfactory when multiple copies are required. Further, it does not possess adequate xerographic copiability on the commercially-available reproduction machines.
The following items to date appear to constitute the most relevant prior art with regard to the instant invention.
U.S. Pat. No. 3,637,748, issued Jan. 25, 1972, discloses and claims a heteryl methane compound which is free of sulphonic acid groups and has the formula ##STR1## wherein R.sub.1 is hydrogen or methyl; R.sub.2 is methyl or phenyl; B stands for a member selected from the group consisting of phenyl, nitrophenyl, chlorophenyl, dichlorophenyl, methoxyphenyl, methylphenyl, hydroxyphenyl, thienyl-2, and furyl-2; D stands for a member selected from the group consisting of 4-methylquinolinyl-methosulphate, 1,2,3,3-tetramethyldihydroindolyl, 1-phenyl-3-methylpyrazolone-(5)-yl, 1-phenyl-2,3-dimethyl-pyrazolone-(5)-yl, substituted naphthyl, substituted phenyl, substituted chlorophenyl, substituted methylphenyl, substituted hydroxyphenyl and substituted ethoxyphenyl, wherein the substituent is located in the 4-position relative to the position at which the CH-group is bound and is a member selected from the group consisting of phenylamino, ethoxyphenyl, amino, methylphenylamino, methylethoxyphenylamino, piperidino, morpholino, mono-alkylamino wherein the alkyl portion contains 1-4 carbon atoms, di-lower alkylamino wherein the lower alkyl portion contains 1-2 carbon atoms, and said mono-alkylamino and said di-lower alkylamino substituted by a member of the group consisting of hydroxy, chloro, cyano and dimethylamino. The heteryl methane compounds are disclosed as being valuable dyestuff intermediates.
U.S. Pat. No. 3,642,823, issued Feb. 15, 1972, discloses and claims an aminodiphenyl-indolyl-methane dyestuff free of sulfonic acid and carboxylic acid groups having the formula ##STR2## wherein R is hydrogen, lower alkyl containing 1-5 carbon atoms, nitro, cyano, benzyl, phenyl, carboxylic acid methyl esters, carboxylic acid ethyl ester, unsubstituted carbonamido, substituted carbonamido containing N-substituents selected from the group consisting of lower alkyl, and lower alkyl substituted with Cl, Br, or OH, methylsulfonyl, ethylsulfonyl, phenylsulfonyl, p-toluene sulfonyl, benzoyl, or acetyl; R.sub.1 and R.sub.2 are both hydrogen; or R.sub.1 is unsubstituted lower alkyl containing 1-5 carbon atoms, substituted lower alkyl containing 1-5 carbon atoms and substituted with Cl, Br or OH, benzyl, naphthyl, phenyl or phenyl substituted with Cl, Br, lower alkyl or lower alkoxy and R.sub.2 is unsubstituted lower alkyl containing 1-5 carbon atoms, substituted lower alkyl containing 1-5 carbon atoms and substituted with Cl, Br, OH, or CN or benzyl; R.sub.3 is hydrogen, lower alkyl containing 1-5 carbon atoms, lower alkoxy, phenyl, phenyl substituted with chlorine, bromine, lower alkyl or lower alkoxy or carboxylic acid methyl or ethyl ester; R.sub.4 is hydrogen, lower alkyl containing 1-5 carbon atoms, lower alkyl containing 1-5 carbon atoms substituted with CN, or benzyl; K, L and M are independently selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, nitro, Cl, and Br, or two of the substituents M are fused to form a naphthalene nucleus; p, q and r are 1 or 2; and X is a substantially colorless anion which does not impair the solubility of the dyestuff in an undesirable manner. The aminodiphenyl-indolyl-methane dyestuffs are described as being useful in the dyeing and printing of materials of leather, tannin-treated cotton, cellulose acetate, synthetic superpolyamides and superurethanes as well as for the dyeing of lignin-containing fibres, such as coconut fibres, jute and sisal. They are also suitable for the production of liquid writing inks, stamping inks, ball point pen pastes and they may also be used in offset printing. Above all they are eminently suitable for the dyeing and printing of materials which are composed partially or completely of polymerized acrylonitrile and/or vinylidene cyanide or which are composed partially or completely of acid-modified aromatic polyesters, such as sulphonic acid group-containing polyethylene terephthalate.
U.S. Pat. No. 3,995,088, issued Nov. 30, 1976, discloses and claims a pressure-sensitive recording material comprising at least one pair of paper sheets containing at least two color formers, dissolved in an organic solvent, and an electron-accepting substance wherein at least one color former is a leuco methylene dyestuff of the formula ##STR3## wherein Y represents an amino-substituted phenyl residue of the formula ##STR4## or an indolyl residue of the formula ##STR5## wherein R.sub.1 and R.sub.2, independently of the other represent hydrogen, alkyl with 1-12 carbon atoms, alkoxyalkyl with 2-8 carbon atoms, benzyl or phenyl; R.sub.3 is hydrogen, halogen, nitro, alkyl having 1-4 carbon atoms or alkoxy having 1-4 carbon atoms; X.sub.1 represents hydrogen, alkyl with 1-12 carbon atoms, alkenyl with at most 12 carbon atoms or benzyl; X.sub.2 represents hydrogen, alkyl with 1-12 carbon atoms or phenyl; the ring A is unsubstituted or substituted by cyano, nitro, halogen, alkyl having 1-4 carbon atoms, alkoxy having 1-4 carbon atoms or acyl with 1-8 carbon atoms; and Z represents alkyl with 1-12 carbon atoms, alkenyl with at most 12 carbon atoms, aryl, aralkyl, a heterocyclic radical or the residue of an organic, particularly aliphatic or cycloaliphatic, compound having a ketomethylene group. The other color former is selected from the group consisting of crystal violet lactone, benzoyl leuco methylene blue, diamino substituted fluoran compounds, 3-phenyl-3-indolylphthalides or 3,3-bis-indolylphthalides or their mixtures thereof.
Whitehead and Whitesilt in the Journal of Medicinal Chemistry 1974 Vol. 17, No. 12, 1298-1304 (1974) describe the preparation and physical characteristics of [bis(phenyl)(2-carboxyindol-3-yl)]methane from the interaction of 2-carboxyindole and benzhydrol in glacial acetic acid. The compound and similar compounds were screened for antimicrobial activity. Toxicity, behavioral effects, antiviral activity, antiinflammatory properties, antispasmatic activity and general endocrine properties of the (diarylmethyl)indoles are described.